Bomb sensor system

ABSTRACT

The system is a remotely operated, autonomous multi-channel time history recording device which uses digital and computer technologies to detect, record and display the results of tests that are time varying dependent. It is particularly suited to monitoring the effects of exploding warheads. By placing a series of piezoelectric detectors in an exploding shock wave field, it is possible to ascertain the wavefront propagation. A dynamic peak detector is used is used with each piezoelectric detector to detect the exact peak of the unknown pulse which peak defines the &#34;time-of-arrival&#34; of the pulse. By controlling the system with a computer program it is possible to display the complete time history of the propagating shock wave. When the exploding device is detonated a counter increments in 100 ns steps with its output on a timing bus. As each piezoelectric detector/peak detector circuit senses the wavefront its respective channel is triggered and the associated data register extracts the time from the timing bus. By linking a computer to the Bomb Sensor System recorded data is available for review within 12.8 seconds after completion of the test. All test results are stored in the memory unit and is transferred to the host computer. Running the computer software program then displays the complete time history of the propagating shock wave. This empirical data when compared to a theoretical analysis reveals any anomalies or validates the test.

RIGHTS OF THE GOVERNMENT

The invention described herein may be manufactured and used by or forthe Government of the United States for all governmental purposeswithout the payment of any royalty.

BACKGROUND OF THE INVENTION

The present invention relates generally to a bomb sensor system.

An antiquated system that triggers Silicon Controlled Rectifiers (SCR's)and uses the time base of an oscilloscope and an operator to judge thesequence of events yields questionable results. Only two channels ofdata could be gathered unless multi-oscilloscopes were used. The resultswere derived by an operator estimating time history. A single sweep ofthe scope of time base setting required to cover the entire time frameof interest would be about 500 micro seconds. Resolving any pulse with a100 nano-second resolution is impossible. This method required aninordinate amount of electronic equipment and support system withresults that were not scientific.

United States patents of interest include U.S. Pat. No. 2,998,719, toRubin, which discloses a shock tube for studying blast effect damage toa target. The device of the Rubin patent is constructed for use with awarhead designed for an aerial missile. Tuck in U.S. Pat. No. 2,703,366times the instant of arrival of a shock wave such as is produced by anexplosion. U.S. Pat. No. 3,447,077 to Loxley et al describes a multiplemissile velocity measuring screen and associated timing apparatus.Thayer in U.S. Pat. No. 3,513,697 measures the maximum pressuredeveloped inside a cartridge when the cartridge is fired within the boreof a suitable firearm. Wirth et al in U.S. Pat. No. 4,725,138 measurethe wavefront of a light beam 8, and D'Ausilio U.S. Pat. No. 4,726,224is directed to a system for testing weapons in space.

SUMMARY OF THE INVENTION

An objective of the invention is to provide a system to record a numberof distinct channels (64) of time interdependence data with a givenresolution (100 nanoseconds). All data must be precise and not subjectedto human discernment.

The invention is directed to a remotely operated, autonomousmulti-channel time history recording device which uses digital andcomputer technologies to detect, record and display the results of teststhat are time varying dependent. It is particularly suited to monitoringthe effects of exploding warheads. By placing a series of piezoelectricdetectors in an exploding shock wave field, it is possible to ascertainthe wavefront propagation. A dynamic peak detector is used to detect theexact peak of the unknown pulse which peak defines the "time-of-arrival"of the pulse. Duplicating the peak detector and associated circuitryonce for each channel (64 were chosen) a multichannel system is formed.By controlling the system with a computer program it is possible todisplay the complete time history of the propagating shock wave.

When the exploding device is detonated a sensor will be triggered andtiming signals will be referenced to this signal (T-O). This electronicpulse enables a counter to increment in 100 nano-second steps(selectable) with its data outputted on a digital timing bus. As eachpiezoelectric detector/peak detector circuit senses the wavefront itsrespective channel is triggered and the associated data registerextracts the precise time (relative to T-O) from the timing bus. After409.5 micro-seconds (selectable) the recording of events is completed.Now after a delay an automatic sequence reads the data stored in theindividual channel data registers and programs the data into anon-volatile memory unit. By linking a computer to the Bomb SensorSystem via aNRS232 link recorded data is available for review within12.8 seconds after completion of the test. All test results are storedin the memory unit and by using the specifically coded software writtenfor this device that data is transferred to the host computer. Runningthe computer software program then displays the complete time history ofthe propagating shock wave. This empirical data when compared to atheoretical analysis reveals any anomalies or validates the test.

This device due to its universal design may be used in any test thatrequires multi-channel information in the time domain. The unit is mostsuitable in the R&D arena where velocity, projectile penetration andscoring information is required.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a block diagram showing a bomb sensor system according to theinvention;

FIG. 2 is a schematic and functional block diagram of the front panelcircuits of FIG. 1;

FIG. 3 is a schematic and functional block diagram of the timinggenerator of FIG. 1;

FIG. 4 is a schematic and functional block diagram of the EPROMcontroller of FIG. 1;

FIG. 5 is a schematic and functional block diagram of the data selectorof FIG. 1;

FIG. 6 is a schematic and functional block diagram of one quad channeltrigger board of FIG. 1;

FIGS. 7a, 7b and 7c are diagrams showing different modes for operationof the peak detectors used on the trigger boards, which are,respectively as a dynamic peak detector, for peak detection withhysteresis, or as a threshold detector; and

FIGS. 8a, and 8c are graphs showing operation of the circuits of FIGS.7a, 7b and 7c respectively.

DETAILED DESCRIPTION

The purpose of this system is to record at least 64 distinct channels oftime interdependence data with a resolution of 100 nanoseconds. All datamust be precise and not subjected to human discernment.

The Bomb Sensor System is a remotely operated, autonomous multi-channeltime history recording device. It uses digital and computer technologiesto detect, record and display the results of tests that are time varyingdependent. The system was explicitly designed to monitor the effects ofexploding warheads, however, the design is flexible enough that it hasmany additional applications.

By placing a series of piezoelectric detectors in an exploding shockwave field, it is possible to ascertain the wavefront propagation. Thesedetectors produce a pulse output of 100-nanosecond duration with anunpredictable amplitude due to the unsymmetrical wavefront distribution.Using a dynamic peak detector it is possible to detect the exact peak ofthe unknown pulse which is now referred to as the "time-of-arrival" ofthe pulse. Duplicating the peak detector and associated circuitry oncefor each channel (64 were chosen) a multichannel system is formed.

Referring to the block diagram of FIG. 1, the 64 peak detectors areorganized on sixteen quad channel trigger boards Q1-Q16, with four peakdetector circuits on each board. Inputs to the 64 peak detector circuitsare via respective connectors BNC1-BNC64, to which the piezoelectricdetectors (not shown) are connected. The input signals are connected tothe quad channel trigger boards via backplane wiring.

A mother board (MB) has circuits including a timing generator (TG), anEPROM controller (EC), and an address and data selector (DS). The motherboard is connected to the quad channel boards via backplane wiring.Mounted on a front panel (FP) and connected to the mother board are afire command circuit 10 having an input BNC connector BNCF, a fireindicator lamp circuit F, a trigger indicator 12, a master reset switch14, a thumbwheel switch 16, a panel switch 18, a plug P1 for a jack J1connected via a RS232 line to a computer, and a power connector 22 forconnection to a 6-volt DC source.

When the exploding device is detonated a sensor (not shown) connected tothe connector BNCF will be triggered and timing signals will bereferenced to this signal (T-0). This electronic pulse enables a counterin the timing generator TG to increment in 100-nanosecond steps(selectable) with its data outputted on a digital timing bus TD0-11. Aseach piezoelectric detector/peak detector circuit senses the wavefrontthe respective channel is triggered and the associated data registerextracts the precise time (relative to T-0) from the timing bus. After409.5 micro-seconds (selectable) the recording of events is completed.Now after a one-second delay an automatic sequencer in the address anddata selector DS reads the data stored in the individual channel dataregisters and programs the data into a non-volatile "ErasableProgrammable Read Only Memory" (EPROM) in the EPROM controller EC. TheEPROM is partitioned into eight sectors selected via the thumbwheelswitch 16, with each sector dedicated to a specific test. Therefore,eight individual tests may be performed before it becomes necessary toreplace or erase the EPROM. By linking a computer to the Bomb SensorSystem via a RS232 link the recorded data is available for review within12.8 seconds after completion of the test. All test results are storedin the EPROM and by using the specifically coded software written forthis device that data is transferred to the host computer. Running thecomputer program then displays the complete time history of thepropagating shock wave. This empirical data when compared to atheoretical analyses reveals any anomalies or validates the test.

The circuits on the front panel FP are shown in FIG.2. The fire commandcircuit 10 is identical to the peak detector circuits on the quadchannel trigger boards. A type CMP02 operational amplifier 30 has aninput coupled to the connector BNCF via a resistor and capacitor, and anoutput to line 9. The fire indicator lamp circuit F includes anindicator lamp 36 connected in series with a resistor 34 between VCCpower and the collector of a transistor 32. The base of the transistoris connected to a line 11, and its emitter is grounded.

The master reset switch 14 is a momentary double pole double throwswitch connecting VCC power and ground to a two-conductor line 15.Momentary operation of the switch reverses the polarity on theconductors of line 15. The thumbwheel switch 16 is used to select asector of the EPROM, using three contacts (with 1K pull up resistors toVCC) binary coded as 1, 2 and 4 to select any value from 0 to 7. Thepanel switch 18 is a single pole double throw switch which in a "EPROM"position connects VCC power to a line 19, and in a "PROG" positionconnects ground to the line.

The plug P1 is a type DB25 having 25 pins, but only the three pins 3, 7and 2 connected to respective conductors of line 21 are shown. The jackJ1 terminates a RS232 line for connection to a computer. The powerconnector 22 provides for connection of a 6-volt battery to the VCCpower lines and ground at the reset switch 14, the mother board MB, andvia the backplane wiring to the quad channel trigger boards.

The trigger indicator 12 has a yellow trigger light coupled via line 13to the quad channel trigger boards, and lights when any channel on anyboard is triggered.

On the mother board, unless otherwise indicated, all NAND gates are typeSN5400, AND gates are type SN5408, and inverters are type 74LS04.

The principal unit of the timing generator TG shown in FIG. 3 is acounter U4. It comprises three 4-bit up/down counter IC chips typeSN54193 cascaded by connecting the carry out terminal CO of each of thefirst two chips to the UP input of the next. The UP terminal of thefirst chip is connected to the output of a NAND gate U3A, and the COterminal of the third chip is connected to an input of an AND gate A3B.The borrow terminals BO (not shown) are not connected. The down countinputs DN are connected to VCC. The four parallel inputs A-D as well asthe clear input CLR of each of the three chips are connected to ground.The LOAD inputs are connected to a line CLEAR, so that a low signal setsthe counter to zero. Each of the three chips has four outputs QA-QD, andthe twelve outputs are coupled via drivers U7 to the 12-conductor lineTD1-11. The drivers U7 comprise seven type SN55461JP chips having twodrivers per chip, with the outputs connected via 50-ohm pull upresistors to VCC. One driver on the seventh chip couples the output ofgate A3A to the line CLEAR.

Two D flip flops U1A and U1B of a type SN5474 chip are used for the firecommand. The D and PR inputs of the two flip flops are connected to VCC.Line 9 from the fire command circuit on the front panel is connected tothe clock input of flip flop U1B, and the Q output of flip flop U1B isconnected to the clock input of flip flop U1A. A positive going pulse online 9 will set the flip flops U1B and U1A in succession. The output offlip flop U1B is connected via line 11 to light the fire lamp on thefront panel. The Q output of flip flop U1A is connected to a line FIREand to an input of gate U3A. An oscillator U2 is a type K1091A Unithaving a 5-MHz crystal. The output of the oscillator is coupled via gateU3A to the UP input of the counter U4, so that in response to the FIREcommand, the counter starts running and advances each 100 nanoseconds.

Two NAND gates U3B and U3C connected as a debounce latch have inputsfrom the two leads of the master reset line 15, and an output from gateU3C connected to the CL input of flip flop U1B and also to an input ofAND gate A3A. The signals from gate U3C and on lead END are normallyhigh and inactive; and when either signal goes low an active low signalfrom gate A3A via a driver appears on lead CLEAR. Gate A3B has inputsfrom lines CLEAR and the CO output of the last stage of the counter U4,and an output to the CL input of flip flop U1A, so that a low signal ateither input of gate A3B resets the signal on line FIRE to stop thecounter.

FIG. 3 also shows two power units 30 and U43 which are used with theEPROM control, each having a a +V IN terminal connected to the +6-voltsource VCC. Unit 30 is a DC/DC converter providing 24 volts output atits terminal +V OUT to line +24V. Unit U43 provides ±12 volts, with itsterminals +V OUT and -V OUT connected respectively to lines +12V and-12V.

The EPROM controller of FIG.4 includes a type 2716 EPROM unit U19. Theunit has eleven address inputs, shown grouped as eight inputs A0-7 andthree inputs A8-10. There are eight terminals O0-O7, shown as O. Controlterminals CE and OE are overlined to indicate active when low. TerminalVPP is connected to an EPROM module unit EM which supplies 24 volts toprogram or write data into the EPROM, and 5 volts to read from thememory U19.

The power input to the EPROM module unit EM is provided from the lines+24V. and VCC. The enable signal on line 19 from the front panel iscoupled via an inverter U26D to an input "ENABLE" of the module EM, witha low signal for inhibit and a high signal for enable. An input terminalVOL. SEL. uses high and low inputs respectively to select 5 volts or 24volts for the output at terminal VPP.

Register unit U15 is a type 54LS374 tri-state octal D-typepositive-edge-triggered flip-flop chip; and register unit U22 is a type54LS273 tri-state octal D-type edge-triggered flip-flop with clear chip.Driver units U14, U20 and U21 are type 54LS244 octal tri-state busdriver chips. The flip flops U18A and U18B comprise a type 54LS74 dualflip-flop chip.

Communication with the computer is provided by a type AY-5-1013Areceiver/transmitter unit U38 The receive lead of line 21 is coupled viaa type MC1489 receiver to an input terminal SDI of unit U38. Theterminal SDO is coupled via a type MC1488 unit U40B to the send lead ofline 21. Unit U40B has the +12V, -12V and ground leads connected to pins14, 1 and 8 respectively. Unit U38 has eight data out terminals DO-0 toDO-7, shown as DO, connected to the eight D inputs of register chip U15;and eight data in terminals DI-0 to DI-7, shown as DI, connected to theeight Y outputs of driver chip U21. Terminal DA is connected to a delayunit B32 and also to the clock terminal of the register unit U15.Terminals RDA and DLS are connected to an output of a one shot unit B26.The receive and transmit clock terminals are connected to the QH outputterminal of a type SN5165 shift register U42, which is also connected tothe serial input terminal SER. The clock terminal is connected to a typeK-1091A crystal oscillator A35 operating at 1.228 MHz, to provide 9600baud operation. Other terminals shown ON shift register U42 are A, B, Cand D connected to VCC; E, F, G, H and INH connected to ground; andSH/not LD connected via a 10 K resistor to VCC This ensures operationwith a 50 duty cycle.

A sector of the EPROM memory unit U19 is selected via thethree-conductor line 17 from the thumbwheel to the address inputs A8-10.The eight address inputs to terminals A0-7 are provided during a writeoperation from the timing generator, via line AD0-7 and the driver unitU14; and during a read operation from the receive/transmit unit U38 viathe registers U15. Data signals to the eight terminals shown as O ofmemory U19 are provided during a write operation via line D0-7 and theregister unit U22; and during a read operation data output is via thedriver unit U21 to the receive/transmit unit U38.

The one-shot units U16 and U26 comprise type SN54221 chips, which aredual non-retriggerable one shots with clear and complementary outputs,all having CLR terminals connected to VCC.

In one-shot unit U16, the two one shots of a chip are connected with theQ output of the first to the A input of the second, the B input of thefirst to lead FIRE, the A input of the first to ground, and the B inputof the second to VCC. The REXT/CEXT terminal of each is connected to thecathode of a type 1N914 diode, with the anode of the diode connected tothe junction of a resistor and capacitor in series from VCC to theterminal CEXT. In the first one shot the resistor has a value of 40.2 Kand the capacitor has a value of 100 microfarads (2 sec), and for thesecond one shot the resistor has a value of 15 K and the capacitor has avalue of 0.1 microfarad (IMS). The Q output of the second one shot isconnected to the clock input of the flip flop U18B.

Flip flop U18B has the D and PR terminals connected to VCC, and the CLterminal to lead CLEAR. The Q output of flip flop U18B is connected toterminal OC of the register unit U15; and the not Q output is connectedto the gate inputs of driver units U14 and U20, and also via invertersU26F and U26G to the VOL. SEL. control input of the EPROM module EM.

In one-shot unit U26, the two one shots of a chip are connected with theQ output of the first to the A input of the second, the B input of thefirst to terminal DA of unit U38, the A input of the first to ground,and the B input of the second to VCC. The REXT/CEXT terminal of each isconnected to the junction of a resistor and capacitor in series from VCCto the terminal CEXT. In the first one shot the resistor has a value of10 K and the capacitor has a value of 180 picofarads (1no), and for thesecond one shot the resistor has a value of 10 K and the capacitor has avalue of 100 picofarad (500NS) The not Q output of the second one shotis connected via a 1 K pull up resistor to VCC, to an input of gateU24A, and to terminals RDA and DLS of unit U38.

A delay unit B32 comprises seven inverters coupled from terminal DA ofunit U38 to the PR terminal of flip flop U18A. Gates U24A and U24B areon a type SN5408 AND gate chip. Gate U24A has an input connected to leadCLEAR and its output to the CL terminal of flip flop U18A, so that whenthe signal at either the output of one shot unit B26 OR on lead CLEAR islow, the flip flop U18A is reset.

Unit U23 shown as a square wave pulse generator, comprises three typeCD4049 inverters and a type CD4013 flip flop. The flip flop has S and Rterminals connected to ground, a D terminal connected to its not Qoutput, and its Q output connected to an input of gate U24B. The threeinverters are in tandem with the output of the last one connected to theclock input of the flip flop. A junction point is connected via a 56 Kresistor to the input of the first inverter, via a 43.6 K resistor tothe output of the last inverter, and via a 0.56 microfarad capacitor tothe point between the output of the second inverter and the input of thelast one.

A delay unit U25 comprises five inverters coupled from the output ofgate U24B to lead INCR, so that when flip flop U18B is set, the pulsesfrom the generator U23 are coupled with delay to lead INCR. An inverterU25D is connected from lead INCR to the CE terminal of the EPROM memoryunit U19.

The Data Selector shown in FIG. 5 comprises a counter and decoders foraddressing the 64 trigger channels is sequence, with two addresses foreach channel.

The counter U27 comprises two type SN54193 synchronous 4-bit binaryup/down counter chips, with the four outputs QA-QD of each shown as Q.The UP count input of the first chip is connected to lead INCR, and thecarry out terminal CO of the first is connected to the UP input of thesecond. The DN count inputs are connected to VCC. The four parallelinputs A-D and CLR inputs of each are connected to ground. The LOADinput of each is connected to lead CLEAR. The four outputs of the firstchip are AD0-3, and the four outputs of the second chip are AD4-7. Theeight leads AD0-7 go to the EPROM Controller of FIG. 4.

There are eight binary-to-1-of-16 decoder chips U30-U37, type SN54154,all having four inputs connected respectively to the four leads A0-3.Each of the decoders U30-U37 has sixteen outputs, eight to each of twoquad channel trigger boards, with the first eight leads from decoder U30shown as lCS0-7 to the first quad board, on so on down to the last eightoutputs of decoder U37 as leads 16CS0-7 to the sixteenth quad board.

A BCD-to-decimal decoder chip U29, type SN5442, has its four inputsconnected respectively to the leads AD4-7. The decoded decimal outputs 1to 8 are connected respectively to the gate inputs of the decodersU30-U37. The output 0 is unused, and the output 9 is used to trigger aone-shot unit A29 to indicate the program end.

The one-shot unit A29 uses only a single one shot of a type SN54221 chipconnected with the not Q output connected to lead END. The A input isconnected to the output 9 of decoder U29, and the B and CLR inputs toVCC. The REXT/CEXT terminal is connected to the cathode of a type 1N914diode, with the anode of the diode connected to the junction of aresistor and capacitor in series from VCC to the terminal CEXT. Theresistor has a value of 15 K and the capacitor has a value of 0.22microfarads.

The Quad Channel Trigger Board Q1 is shown in FIG. 6. The sixteen boardsare the same, and the four channels on each board have the same circuit,so only the first channel circuit CH1 is shown in detail. The principalcomponent is a type CMP02 operational amplifier V2 used as a comparator.The BNC connector BNC1 is connected via a 0.01 microfarad capacitorRP1d, a type DDU-1504-100 delay device V1 which provides a 100nanosecond delay, and a 5 K resistor R2 in series to the + input of theOP Amp V2. The--input is connected via parallel 5 K resistors RP1a andRP1c to VCC, and also via a 5 K resistor RP1b to ground. A 820 Kresistor R1 provides feedback from the output to the + input. Pin 8 isconnected to VCC and via a 0.1 microfarad capacitor to ground. Pins 1and 4 are connected to ground, and pins 5 and 6 are connected together.The output goes to the clock input of a type 54LS74 flip flop V3A. Theflip flop has the D and PR inputs connected to VCC, and the CL input tolead CLEAR.

Each quad channel trigger board has eight tri-state octal D-typetransparent latches, type 54LS373, shown as registers 1R0-1R7 for boardQ1 in FIG. 6. The not Q output from the flip flop of channel CH1 isconnected to the gate input G of the first two registers 1R0 and 1R1,and the outputs of the other channels are each in like manner connectedto the G inputs of two of the register units.

The two register units for each channel are used to store time values,which are binary coded on line TD0-11 using 12 bits. The eight D inputsfor the first register of each channel, such as register 1R0 for channelCH1, are connected respectively to leads TD0-7, and the first four Dinputs of the second register, such as register 1R1 for channel CH1, areconnected respectively to leads TD8-11. The other four D inputs of thesecond register of each pair are grounded, but could be used to expandthe timing bus to 16 bits, and are shown as bits TD12-15 to ground. Thetri-state outputs of the register units may be enabled to read the datato line D0-7, using address signals to the inputs OC, with OC inputs ofregister units 1R0-1R7 being connected respectively to the eight leadsof line 1CS0-7.

A light emitting LED diode DP1g used as a trigger indicator has itsanode connected to VCC, and its cathode connected via a 330-ohm resistorto the anodes of four type 1N914 diodes DP1a-DP1d, which have theircathodes connected respectively to the outputs of the four channelsCH1-CH4. A fifth type 1N914 diode DP1e has its cathode connected toresistor DP1f, and its anode connected via line 13 to the triggerindicator on the front panel.

OPERATION

Inter-connect each piezo-electric detector to the Bomb Sensor System viaBNC connectors BNC1-BNC64 respectively. Connect a +6VDC battery tosystem via connector 22 "Power Plug." Turn power switch 14 on, the unit(FIG. 3) generates a power up reset at lead CLEAR. This resets theentire unit. If during operation it becomes necessary to reset thesystem un-guard switch 14 RESET/CLEAR and toggle. All channel card LED's(FIG. 6), and Yellow trigger light of unit 12 (FIG. 2) extinguish. Turnswitch 18 "EPROM PROG" to program. The unit is now armed and ready totake data. When a fire command is sensed comparator 30 of the firecommand circuit 10 (FIG. 2) triggers when the peak signal is detectedThe CMP-02 peak detector may be operated in several modes, as shown inFIGS. 7a to 8c.:

After the peak is sensed counter U4 (FIG. 2) is enabled via lead 9, flipflops U1A and U1B, and gate U3A, and starts to increment at theoscillator U2 rate (100 ns/pulse). Line drivers U7 provide the drivecurrent for the timing bus TD0-11. The timing bus is available to eachof the quad channel input trigger boards Q1-Q16. When a specific channelpiezoelectric sensor detects an over pressure, that pulse is applied toits corresponding peak detector, via its BNC connector which toggles itsrespective latch (eliminating multiple triggering) and latches in thedigital timing signal present at that time on the timing bus. Forexample, if a detected pulse is received at the connector BNC1 forchannel CH1, the flip flop V3A is set, and register units 1R0 and 1R1are gated to store the time value then present on the timing bus TD0-11.Each quad channel input trigger board has a LED that illuminates if anyone of the four inputs trigger. The master trigger light of unit 12 onthe front panel illuminates if any quad channel trigger board had senseda trigger. At the end of count 4095 the counter U4 (FIG. 2) input isdisabled by flip flop U1A being reset in response to the carry outsignal from counter U4 via gate A3B. At this time each channel that hastriggered has stored its time in a temporary holding register (such asregisters 1R0 and 1R1 of FIG. 6 for channel CH1 and correspondingregisters on this and the other quad channel trigger input boards forthe other channels).

After a two-second delay generated by the one-shot unit U16 (FIG. 4),flip flop U18B is set and the programming of the EPROM memory U19starts. Driver units U14 and U20 are enabled, and register unit U15 istri-stated to the high-impedance output state. EPROM module EM isprogram enabled (24V out at VPP) via inverters U26F and U26E. Theprogramming oscillator U23 free runs at 10 Hz with a 50% duty cycle butis locked out by gate U24B until in the programming mode. At this timethe EPROM address register U27 (FIG. 5) is at zero (power up reset). Thedelay unit U25A provides a 50 ns delay required to allow the data tostabilize before using. The programming of the EPROM memory U19 issequential, from the first address to the last. Procedures forprogramming are automatic and sequenced as follows:

(1) Set EPROM address counter U27 (starts at zero due to power-upreset).

(2) Transfer the address to the EPROM memory U19 via the driver unitU14.

(3) Select the quad channel decoder (FIG. 6). The decoder U29 decodesthe EPROM address and every 16 counts increments to a new output whichin turn enables the decoder chain comprising the ten decoders U30-U37.The quad channel timing registers (registers 1R0-1R7 of FIG. 6 andcorresponding registers on the other quad channel trigger boards)transfer their contents to the register unit U22 in 8-bit bytes, i.e.,Hi byte, Lo byte. When the register U22 clock pulse goes high the quadchannel register data is latched into register U22 and transferred tothe EPROM memory U19 via driver unit U20. After the 50 ns delaygenerated by the delay unit U25 the programming pulse is applied via theinverter U25D to the CE input of the EPROM memory U19.

(4) The EPROM address counter U27 is incremented by a pulse from unitU25 via the lead INCR.

(5) Steps 2 through 5 repeat until the decoder U29 decodes the 9th countof 16 from the counter U27 which is the count of 144. This equals a 16count buffer (note the 0 output of the decoder U29 is not used) followedby a high byte (i.e., lead 1CS0) then a 1o byte (i.e., lead 1CS1) foreach of the 64 channels. When unit U29 has decoded the proper count andhas advanced to output 9, a reset pulse is generated by the One Shotunit A29 via lead END to the gate A3A (FIG. 3) and a driver of unit U7to lead CLEAR.

At this time the system is transitioned to the computer read mode. Thesignal on lead CLEAR resets flip flop U18B, and the low signal at its Qoutput inhibits gate U24B to disable the programming oscillator U23. Thesignal from the not Q output of flip flop U18B via inverters U26F andU26E goes high, causing the EPROM module EM to output 5V at terminalVPP, which sets the EPROM U19 to the read mode. The signals from flipflop U18B also cause the drivers U14 and 20 to be tri-stated and driverU15 to be enabled. Oscillator A35 and shift register U42 sets thecorrect frequency for the Universal Asynchronous Receiver Transmitter(UART) U38 to operate at 9600 baud rate. The UART U38 is hard wired for8 data bits, 1 stop bit and no parity. Computer read of the EPROM U19may be random or sequential depending on the computer operator'spreference. The computer operator will transmit the address he wants toread via the RS232 link and line 21. The unit U41A receives the serialdata and converts the data to TTL levels. The UART U38 takes the serialdata in at terminal SDI, and outputs it in 8-bit parallel at the set ofterminals DO to the register unit U15. When the data is valid a signalat terminal DA goes high and latches the data into registers U15. Theoutput of register unit U15 becomes the address A0-7 of the EPROM U19.After a 70-nanosecond delay, generated by unit B32, the flip flop U18Ais set, to provide a low signal to the output enable terminal of theEPROM U19. The data at the specific address is coupled via transparentlatches of the driver unit U21 to the set of DI terminals of the UARTU38. After a one-microsecond delay, the one shots of unit B26 produce a500-nanoseconds pulse to terminal DLS of UART U38, which latches thedata and subsequently transmits the data in serial fashion from terminalSDO to the computer via the unit U40B, line 21 and the RS232 link. TheUART U38 is reset and is now ready to receive the next command word.

ADVANTAGE AND NEW FEATURES. The system according to the invention hasthe ability to detect and output data that is not subjected to personalinterpretation. All data is precise and accurate to ±50 ns. The manualsystem previously employed uses a host equipment and peripheral supportdevices yet has a recording capability of 4 channel and an accuracy of 1micro-second. This invention provides a 16 to 1 increase in recordingcapacity and a 20 fold increase in precision. Reduction of data isautomatic via computer software and essentially available in real time.Required support is limited to the single unit, Bomb Sensor System,which is integrated it a ruggedized chassis box approximately 19"×20"×7"and a 6VDC storage battery.

ALTERNATIVES. Rearranging the peak detector configurations as shown inFIGS. 7a to 8c allows for any variety of applications that requireprecise timing. The system as built has a 12-bit timing bus, however,this could be expanded to 16 bits by adding 4 wires to each quad channeltrigger board and adding 1 integrated circuit. This would increase thedata register capacity from 4096 bytes to 65,536 bytes. Data accuraciescould be improved to ±25 ns by changing the master clock frequency from10 MHz to 20 MHz. A majority of R&D test require a timed sequence ofevents. Therefore, this invention has the potential for universalapplication on tests that have a time correlation recording requirement.

It is understood that certain modifications to the invention asdescribed may be made, as might occur to one with skill in the field ofthe invention, within the scope of the appended claims. Therefore, allembodiments contemplated hereunder which achieve the objects of thepresent invention have not been shown in complete detail. Otherembodiments may be developed without departing from the scope of theappended claims.

What is claimed is:
 1. A bomb sensor system for monitoring the effectsof exploding devices and ascertaining the wavefront propagation bysensing the wavefront at a given number of points using a channel foreach point, wherein said system comprises;peak detector means individualto each channel for detecting the peak of a pulse associated with thewavefront to define the time of arrival at the point for the individualchannel; timing means comprising a counter, a timing pulse sourceproviding a train of timing pulses at a given interval, timing inputgate means coupling the timing pulse source to a clock input of thecounter, a timing bus comprising N conductors coupled to paralleloutputs of the counter on which a count value is encoded; command meanscomprising fire detector means for detecting detonation of an explodingdevice and means set in response thereto for enabling the input gatemeans to start the counter running at a time designated t0; channelregister means individual to each channel, each having N parallel datainput terminals coupled to the timing bus, a gate control terminal forcontrolling the loading of data, an output control terminal for enablingplacing the data on a data bus, the gate control terminal being coupledto the peak detector means to load the the count value from the timingbus upon the detection of the peak of a pulse to thereby record the timewith respect to T0.
 2. A bomb sensor system according to claim 1,further including data selector means coupled to the output controlterminals of the channel register means for addressing the channelregister means of each channel in turn and reading the data onto thedata bus;a memory unit having a set of address inputs coupled to thedata selector means, and data terminals coupled to the data bus forstoring the data from the channel register means as each channel isaddressed by the data selector means.
 3. A bomb sensor system accordingto claim 2, further including transceiver means coupling the memory unitto a computer interface line for receiving addresses from a computer andcoupling them to the memory unit, and for reading data from the memoryunit for each address and supplying it to the computer.
 4. A sensorsystem for monitoring an event at a plurality of points using a channelfor each point wherein said system comprises;detector means individualto each channel for detecting a pulse associated with the event todefine the time of arrival at the point for the individual channel;timing means comprising a counter, a timing pulse source providing atrain of timing pulses at a given interval, timing input gate meanscoupling the timing pulse source to a clock input of the counter, atiming bus comprising N conductors coupled to parallel outputs of thecounter on which a count value is encoded; command means comprisingstart detector means for detecting a start of an event and means set inresponse thereto for enabling the input gate means to start the counterrunning at a time designated t0; channel register means individual toeach channel, each having N parallel data input terminals coupled to thetiming bus, a gate control terminal for controlling the loading of data,an output control terminal for enabling placing the data on a data bus,the gate control terminal being coupled to the detector means to loadthe the count value from the timing bus upon the detection of a pulse tothereby record the time with respect to T0; data selector means coupledto the output control terminals of the channel register means foraddressing the channel register means of each channel in turn andreading the data onto the data bus; a memory unit having a set ofaddress inputs coupled to the data selector means, and data terminalscoupled to the data bus for storing the data from the channel registermeans as each channel is addressed by the data selector means;transceiver means coupling the memory unit to a computer interface linefor receiving addresses from a computer and coupling them to the memoryunit, and for reading data from the memory unit for each address andsupplying it to the computer.